Direction signal mechanisms



DIRECTION SIGNAL MECHANISMS William E. Brown and Ward Cole, Anderson, Ind., as-

signors to General Motors Corporation, Detroit, Mich., a corporation of Delaware- Application September 11, 1953, Serial No. 379,608

3 Claims. (Cl. ZOO-61.34)

The present invention relates to direction signal control mechanisms and more particularly, although not exclusively, to improvements in direction signal control mechanisms of the type described in the co-pending application of David C. Redick, entitled, Direction Signaling Device, Serial Number 251,785, filed October 12, 1951.

Direction signal mechanisms of the type referred to are provided with an operating member having yieldable pawls which are plvotally mounted thereon for cooperation with a rotatable cancelling pin, carried by the steering member. When the mechanism is placed; in an operating position, these pawls are adapted to be rotatively displaced in one direction and to resist rotation in the opposite direction. In the past it has been the practice to fabricate such pawls by stamping from sheet metal, die casting or other suitable means, As a result of exhaustive tests, it

has been determined that a large percentage of malfunctions of direction signal control mechanisms are attributable to unsatisfactory function of the pawls during the cancelling action. Careful examination of the pawls of numerous mechanisms disclosed relatively wide variation in shape and tolerances. production of metal pawls by standard production techniques dictates configurations havingrelatively narrow cancelling pin contact surface. Still another shortcoming of metal pawls is the necessity of applying a suitable lubricant during the assembly operation and. possibly at subsequent intervals. Finally, metal pawls produce an annoying metallic clickingv as the steering wheel is rotated.

One object of the present invention is to provide a novel and improved direction signal switch mechanism of the manually set and automatically re-set type which is exceptionally smooth and silent in operation.

Another object is to provide a mechanism of the type described having cancelling means formed and constructed in a manner providing greatly improved consistency of operation.

Another object is to provide a direction signal switch mechanism of the stated character wherein the re-setting means includes rotatable pawls formed of material requiring no lubrication.

Still another object isto provide a direction signal switch mechanism having rotatable cancelling pawls formed of material capable of being formed to very close tolerances at very low cost.

A further object is to provide a direction signal control mechanism of the type described wherein the operating surfaces of the cancelling pawlsare formed in a manner adapted to greatly reduce the incidence of malfunction thereof.

These and other objects and advantages of the invention will become apparent from the following description, reference being had to the accompanying drawings wherein:

Fig. l is a plan view, partly in section, of the signal control mechanism, showing the position of the parts thereof when the mechanism is in neutral position.

In addition, economical 2,757,250 Patented July 31, 1956 Fig. 2 is an enlarged sectional elevational view taken substantially along the lines 22 of Fig. 1, and

Fig. 3 is an enlarged fragmentary sectional elevational view of the pawl structure, looking in the direction of arrows 33 of Fig. 1.

Referring now to the drawings and particularly Figs. 1 and 2, there is illustrated a direction signal control mechanism comprising a housing 2 secured near the upper end of a vehicle steering column indicated generally at 3. Integrally formed in housing 2 is a web 4 having a central opening 6 adapted for sleeved engagement with the upper end of steering column 8. Interiorly of housing 2 is a generally circular operating ring 10 adapted for swingable movement therein. An operating handle 12 extends through a slot 14 in the housing and is coincidentally secured with ring 10 to a stud 16 journalled in web 4.

Substantially opposite stud 16, ring 10 is provided with an upwardly ofi-set portion 18 adapted to carry a roller 20. A formed retaining spring 22 is transversely secured in the housing 2 and is provided with an undulating midportion 24 which yieldably cooperates with roller 20 to yieldably retain ring 10 in the central neutral position and operating positions at either side of the neutral position.

Directly beneath the spring 22, ring 15') is provided with a slot 25 adapted to engage an upwardly extending operating pin 26 of a switch 27. Pin 26 is integrally formed on a bridging member 23 which, in turn, is slidably disposed in a switch casing 30 and adapted for movement to a plurality of positions corresponding to the respective positions of the ring 10. Switch casing 30 is secured in the web 4 by any suitable means such as machine screws 32. Switch 27 is of the type commonly utilized in direction signal systems, a more complete description of which may be had by reference to the co-pending application of David C. Redick, entitled Direction Signaling Device, Serial Number 251,785, filed October 12, 1951.

Substantially mid-way between stud 16 and roller 20, ring 10 is provided with a pair of diametrically opposite studs 34 and 36 upon which are rotatably secured a pair of reversely similar pawl members 40 and 42, the construction of which will be more fully described later herein. Pawls 40 and 42 are yieldably retained in a predetermined angular position by light coil springs 44 and 46 which extend between the said pawls and anchor brackets 48 and 50 riveted to the body of ring 10. To provide relatively high resistance to rotation of the pawls in one direction, anchor brackets 48 and 59 are provided with stifi blade portions 52 and 54, having free ends 53 and 55 which intersect the path of rotation of said pawls in one direction. Thus, pawls 4t) and 42 are relatively freely rotatable in one direction and normally nonrotatable in the reverse direction. However, in the event that sufiicient force is applied to the said pawls in the opposite direction, blade spring end portions 53 and 55 will yield outwardly to permit reverse rotation of the pawls.

To provide for automatic cancelling of a manually set signal, a circular disc 60 is secured to the base of the steering wheel 62, which, in turn, is attached to the end of the steering shaft 64. Downwardly depending from the disc 60 are a pair of depending ears 66 which are adapted to rotate interiorly of the housing 2 in a circular orbit. When ring 10 is in the neutral position, the circular path of ears 66 is unobstructed. However, when ring 10 is moved to either the right or left operating position, the inwardly directed lobe portion 65 or 67 of pawl 40 or 42, as the case may be, is moved to a position intersecting the orbit of said ears. Therefore, upon engagement, in one direction, of the lobe portion 65 or 67 by ears 66, the pawl 40 or 42 will be rotatively displaced to permit continued rotation of the ears. Upon the lobe portion 65 or 67 from the opposite direction. Since blade spring 52 or 54 normally resists reverse rotation of the pawl, ring will be swingably displaced outwardly to the neutral position to permit passage of ears 66.

Since the proper function of a mechanism of this type is largely dependent upon consistent interaction between ears 66 and the lobe portion 65 or 67 of pawls 40 or 42, it is especially important that variations in form of the pawls be reduced to a minimum and that the maximum surface engagement be provided between the lobe 65 or 67 and the depending ear 66. In view of the high degree of wear incident to prolonged use of a device of this type, it is also desirable that the pawls be highly resistant to wear in order to assure retention of the original accurate relationship. Therefore, in accordance with the present invention, pawls 40 and 42 are constructed of a solid nylon, a polyamide resin produced by the controlled polymerization of a mixture of adipic acid and hexamethylene cliamide. To assure maximum accuracy in formation and extremely economical production, it is preferable that the pawls be produced by a molding process. In this connection, it has been found that the powdered form of polyamide resins is particularly adapted to the fabrication of such parts.

As seen best in Figs. 1 and 3, pawls 40 and 42 are formed with fiat, relatively thin body portions 68 and 70 and are contoured to provide wedge-shaped lobe portions 65 and 67 and apertured spring-engaging portions 74 and 76. Centrally thereof, body portions 68 and 70 are provided with circular apertures 78 and 80 permitting the pawls to be journalled on the reduced end portions 84 of stud collars 85. Along the boundary defining the lobe portions 65 and 67, pawls 40 and 42 are formed with integral, relatively broad vertical ribs 86 and 88 which are adapted for wiping engagement with cancelling ears 66. Because of the substantially increased area provided by ribs 86 and 88 at the boundary of lobes 65 and 67, materially improved surface engagement is had between the ears 66 and the lobes 65 and 67 during the cancelling operation of the mechanism, thus reducing the likelihood of failure of the mechanism to cancel.

By utilizing molded nylon, pawls of complex configuration may be produced at costs comparing favorably with the more elementary forms of metal pawls previously employed in direction signal mechanisms. In contrast to the relatively simple process required to mold the present type of pawl, the fabrication of even a flat metal pawl requires blanking, flattening, heat treating and penetrating blueing in order to produce a finished part. Therefore, it will be apparent that to form a metal pawl having the improved qualities provided by a broadened cancel,- ling rib, would involve still further processing, which would tend to increase the possibilities of variation in tolerances as well as rendering the unit costs prohibitive.

in addition to permitting economical production and assuring greater consistency of close tolerances, molded nylon pawls have the additional advantages of being highly wear resistant, requiring no lubrication and contributing substantially to a more silent operation than may be obtained with a metal pawl.

From the foregoing description, it will be seen that there has been provided an improved and simplified direction signal mechanism having greater initial precision and substantially increased operating life.

While but a single embodiment has been shown and described, it is to be understood that other modifications may be adopted without departing from the scope of the invention. Therefore, it is not intended to limit the invention to the single embodiment shown, but only by the scope of the claims which follow.

We claim:

1.. In a switch operating member, the combination of a substantially flat ring, a pair of pivotal pawls disposed oppositely on said ring, said pawls being constructed of self-lubricating plastic material, rotatable means for actuating said pawls, said pawls having integral ribbed portions formed thereon adapted for wiping engagement with said actuating means, spring means normally retaining said pawls in a predetermined centered position, and additional spring means adapted to permit rotation of said pawls in one direction and resist rotation of said pawls in the opposite direction.

2. In a device of the class described, the combination of a switch movable from an open neutral position to circuit closing positions at opposite sides of said neutral position, an operating handle for said operating member, pivotal means for mounting said operating member on said fixed support, means on said pivotal means for simultaneously securing said operating handle and said operating member to said pivotal means, molded nylon pawls pivotally mounted at opposite sides of said operating member, resilient means on said operating member to yieldably resist rotation of said pawls in one direction, a steering wheel, signal cancelling lugs on said steering wheel, spring means for yieldably retaining said pawls in such position as to cause engagement of one of said pawls by said lugs when said operating member is adjusted to one of its switch closing positions and to cause engagement of the other of said pawls by said lugs when said operating member is adjusted to the other of its switch closing positions.

3. In a device of the class described, the combination of a switch movable from an open neutral position to circuit closing positions at opposite sides of said neutral position, a fixed support, an operating member for said switch, oppositely disposed pawls pivotally mounted on said operating member, said pawls being formed of selflubricating plastic material, lobe portions formed on said pawls, said pawls having integral ribbed portions defining the boundary of said lobe portions, flexible means on said operating member adapted to normally abut said pawls, a steering wheel, means connected to said steering wheel having operating lugs thereon, and means for yieldably retaining said pawls in such position as to cause engagement of one of said ribbed portions by said lugs when said operating member is adjusted to one of its switch closing positions and to cause engagement of the other of said ribbed portions by said lugs when said operating member is adjusted to the other of its switch closing positions.

References Cited in the file of this patent UNITED STATES PATENTS 2,133,469 Obergfell Oct. 18, 1938 2,264,225 Thirwell Nov. 25, 1941 2,343,355 Yanchenko et al. Mar. 7, 1944 2,427,595 Fuller Sept. 16, 1947 2,643,308 Lincoln et al. June 23, 1953 2,657,287 Lincoln et a1 Oct. 27, 1953 2,690,483 Elliott et a1. Sept. 28, 1954 FOREIGN PATENTS 150,932 T Australia Apr. 16, 1953 OTHER REFERENCES Product Engineering, Nov. 1950, page 229. Product Engineering, Sept. 1948, page 140. 

